Wireless communication system, mobile station device, and base station device

ABSTRACT

A base station device includes: a control information generating section which generates control information specific to mobile station devices; a control information count indicator generating section which generates a control information count indicator indicating the number of pieces of generated control information of each mobile station device; and a transmitting section which transmits the control information count indicator and the control information. The mobile station device includes: a receiving section which receives a control information count indicator and control information transmitted from the base station device within a mobile station-specific search space selected based on a mobile station ID of the mobile station device; a control information count indicator detecting section which detects the control information indicator; and a control channel decoding section which decodes the control channel in response to the number of pieces of detected control information.

TECHNICAL FIELD

The present invention relates to a wireless communication system, amobile station device, and a base station device.

This application claims priority to and the benefits of Japanese PatentApplication No. 2008-278517 filed on Oct. 29, 2008, the disclosure ofwhich is incorporated herein by reference.

BACKGROUND ART

Wideband code division multiple access (W-CDMA) schemes, which are thirdgeneration (3G) radio access schemes of cellular mobile communication,have been standardized in 3rd Generation Partnership Project(hereinafter, referred to as 3GPP), and cellular mobile communicationservices by the same scheme have been initiated. In 3GPP, the evolutionof 3G (hereinafter, referred to as evolved universal terrestrial radioaccess (EUTRA)) and the evolution of a 3G network (hereinafter, referredto as evolved universal terrestrial radio access network (EUTRAN)) havebeen studied.

An orthogonal frequency division multiplexing (hereinafter, referred toas OFDM) scheme of multicarrier transmission is used in a downlink oftransmission from a base station device of EUTRA to a mobile stationdevice. A single-carrier communication scheme of a discrete Fouriertransform (DFT)-spread OFDM scheme of single-carrier transmission isused in an uplink of transmission from a mobile station device of EUTRAto a base station device.

In 3GPP, a 4th generation (4G) radio access scheme of cellular mobilecommunication (advanced EUTRA (hereinafter, referred to as “A-EUTRA”))and a 4G network (advanced EUTRAN) has started to be studied.

In A-EUTRA, a study has been made to deal with a frequency band, whichis wider than that of EUTRA, and to secure compatibility with EUTRA. Amobile station device corresponding to EUTRA, which communicates with abase station using part (hereinafter, referred to as a “subband”) of afrequency band of the base station device, and a mobile station devicecorresponding to A-EUTRA, which communicates with a base station deviceusing one or more subbands of the base station device, have beenproposed. That is, the base station device, which controlstransmission/reception of the mobile station device, performstransmission/reception to/from the mobile station device correspondingto EUTRA using any one subband, and performs transmission/receptionto/from the mobile station device corresponding to A-EUTRA using one ormore subbands in response to capability of the mobile station device,which performs transmission/reception. That is, the base station deviceuses all subbands by allocating several resources (a resource block) ofa subband to the mobile station device corresponding to EUTRA in eachsubband and allocating several separate resources, which are not yetallocated to the mobile station device corresponding to EUTRA, to themobile station device corresponding to A-EUTRA. However, the number ofresources to be allocated is changed in response to capability of themobile station device corresponding to A-EUTRA since the number ofsubbands capable of being simultaneously transmitted and received isdifferent even in the mobile station device corresponding to A-EUTRA.

A layered OFDM scheme, which uses OFDM of multicarrier transmission in adownlink of transmission from a base station device to a mobile stationdevice in A-EUTRA and performs communication using a plurality offrequency bands, has been proposed (see Non-Patent Document 1).

FIG. 15 is a diagram showing a schematic configuration of a downlinkradio frame in EUTRA. In FIG. 15, the horizontal axis represents afrequency domain and the vertical axis represents a time domain. Thedownlink radio frame is a unit of radio resource allocation or the like,and includes physical resource block (hereinafter, referred to as “PRB”)pairs including a frequency band and a time band having predeterminedwidths. One PRB pair includes 2 PRBs continuous in the time domain.

One PRB includes 12 subcarriers in the frequency domain and includes 7OFDM symbols in the time domain. A system bandwidth is a communicationbandwidth of the base station device. In the time domain, a slotincludes 7 OFDM symbols, a subframe includes 2 slots, and a radio frameincludes 10 subframes. A unit including 1 subcarrier and 1 OFDM symbolis referred to as a resource element. In a downlink radio frame, aplurality of PRBs are arranged in response to the system bandwidth.

In each subframe, at least a downlink shared data channel used intransmission of information data and a downlink control channel used intransmission of control data are arranged. Although not shown in FIG.15, downlink pilot channels used in channel estimation of the downlinkshared data channel and the downlink control channel are distributed andarranged in a plurality of resource elements. The case where thedownlink control channel is arranged in first, second, and third OFDMsymbols of the subframe, and the downlink shared data channel isarranged in other OFDM symbols is shown in FIG. 15, but the OFDM symbolsin which the downlink control channel is arranged may vary in a subframeunit.

Although not shown in FIG. 15, a control format indicator channelindicating the number of OFDM symbols constituting the downlink controlchannel is arranged in the first OFDM symbol. The downlink controlchannel may be arranged in only the first OFDM symbol or may be arrangedin the first and second OFDM symbols. In the same OFDM symbol, thedownlink control channel and the downlink shared data channel are notarranged together. In the downlink control channel, a mobile station ID,radio resource allocation information of the downlink shared datachannel, multi-antenna-related information, a modulation scheme, acoding rate, a retransmission parameter, and the like are arranged.

The downlink control channel is constituted by one or more controlchannel elements (CCEs). The number of CCEs depends upon the systembandwidth, the number of OFDM symbols constituting the downlink controlchannel, and the number of downlink pilot channels corresponding to thenumber of transmission antennas of the base station device used incommunication. The CCE is constituted by a plurality of resourceelements.

FIG. 16 is a diagram illustrating a logical relationship between theCCEs and the downlink control channel in EUTRA. Here, CCE n indicates aCCE of CCE index n. The CCE index is a CCE identification number.

The downlink control channel is constituted by an aggregation includingone or more CCEs. The number of CCEs constituting the aggregation ishereinafter referred to as a “CCE aggregation number.” The CCEaggregation number constituting the downlink control channel isdetermined in response to a coding rate and an amount of control data.An aggregation including n CCEs is hereinafter referred to as “CCEaggregation n.” For example, the downlink control channel is constitutedby 1 CCE (CCE aggregation 1), the downlink control channel isconstituted by 2 CCEs (CCE aggregation 2), the downlink control channelis constituted by 4 CCEs (CCE aggregation 4), or the downlink controlchannel is constituted by 8 CCEs (CCE aggregation 8).

The CCE is constituted by a plurality of resource element groups (alsoreferred to as mini-CCEs). FIG. 17 is a diagram illustrating anarrangement example of resource element groups in a downlink subframe byEUTRA. Here, the case where the downlink control channel is constitutedby first to third OFDM symbols and downlink pilot channels of 2transmission antennas (transmission antenna 1 and transmission antenna2) are arranged is shown. In FIG. 17, the horizontal axis represents afrequency domain and the vertical axis represents a time domain. In thearrangement example of FIG. 17, 1 resource element group is constitutedby 4 resource elements and is constituted by adjacent resource elementsof the frequency domain.

If resource elements are denoted by the same reference numeral as thatof the downlink control channel in FIG. 17, it indicates that theresource elements belong to the same resource element group. A resourceelement group is configured by skipping a resource element R1 (adownlink pilot channel to be transmitted from transmission antenna 1)and a resource element R2 (a downlink pilot channel to be transmittedfrom transmission antenna 2) in which the downlink pilot channels arearranged.

In FIG. 17, numbering (reference numeral “1”) is performed from aresource element group of a first OFDM symbol having a lowest frequency.Next, a resource element group of a second OFDM symbol having a lowestfrequency is numbered (reference numeral “2”). Next, a resource elementgroup of a third OFDM symbol having a lowest frequency is numbered(reference numeral “3”).

Next, a resource element group is numbered (reference numeral “4”)adjacent in the frequency axis to the resource element group (referencenumeral “2”) in which the second OFDM symbol in which no downlink pilotchannel is arranged is numbered. Next, a resource element group isnumbered (reference numeral “5”) adjacent in the frequency axis to theresource element group (reference numeral “3”) in which the third OFDMsymbol in which no downlink pilot channel is arranged is numbered.

Next, a resource element group is numbered (reference numeral “6”)adjacent in the frequency axis to the resource element group (referencenumeral “1”) in which the first OFDM symbol is numbered. Next, aresource element group is numbered (reference numeral “7”) adjacent inthe frequency axis to the resource element group (reference numeral “2”)in which the second OFDM symbol is numbered. Next, a resource elementgroup is numbered (reference numeral “8”) adjacent in the frequency axisto the resource element group (reference numeral “3”) in which the thirdOFDM symbol is numbered. Likewise, resource element groups of subsequentPRB pairs are also numbered.

The CCE is constituted by a plurality of resource element groupsconstituted as shown in FIG. 17. For example, 1 CCE is constituted by 9different resource element groups distributed in the frequency domainand the time domain. Specifically, all resource element groups numberedas shown in FIG. 17 in the entire system bandwidth are interleaved usinga block interleaver in a resource element group unit, and 1 CCE isconstituted by 9 resource element groups whose numbers are continuousafter interleaving.

The mobile station device demodulates and decodes a reception signalunder assumption of a plurality of downlink control channels capable ofbeing allocated to its own mobile station device for CCEs received ineach subframe, and performs a cyclic redundancy check (hereinafter,referred to as “CRC”) of checking whether or not it is a downlinkcontrol channel allocated to its own mobile station device using a CRCcode added to the downlink control channel. Specifically, the basestation device generates the CRC code from control data using apredetermined generating polynomial, adds information (CRC masked by UEID) obtained by an exclusive OR operation of the generated CRC code anda mobile station ID of the mobile station device to which a downlinkcontrol channel is allocated to the downlink control channel,multiplexes the downlink control channel into a CCE, and transmits theCCE. By performing the inverse processing of the above-describedoperation, the mobile station device receiving the CCE from the basestation device performs error detection and also detects whether or nota downlink control channel addressed to its own mobile station device ismultiplexed and transmitted.

For example, in the case of a downlink control channel as shown in FIG.16, a reception signal is demodulated, decoded, and CRC-checked for atotal of 15 CCE combinations of 8 CCE aggregations 1, 4 CCE aggregations2, 2 CCE aggregations 4, and 1 CCE aggregation 8 in terms of CCEs 1 to 8under the assumption that the downlink control channel is multiplexedand transmitted. This processing is referred to as blind decoding of thedownlink control channel, and the number of times of blind decoding isincreased with an increase of the number of possible CCEs.

Here, a modulation scheme of the downlink control channel is fixed andseveral candidates for a coding rate are set for each CCE aggregationnumber. Accordingly, when the blind decoding is performed, decoding anda CRC check are performed at each candidate coding rate corresponding toa CCE aggregation number for each CCE combination. That is, if thenumber of candidate coding rates corresponding to a CCE aggregationnumber of a certain CCE combination is 2, decoding and a CRC check areperformed for the CCE combination using each of the 2 coding rates, sothat decoding and a CRC check are performed in two ways for the CCEcombination. At this time, the coding rate varies with an amount ofcontrol data to be transmitted on the downlink control channel. Sincethe coding rate is determined by the CCE aggregation number if theamount of control data of the downlink control channel is fixed,decoding and a CRC check are performed in one way for each CCEcombination. When the system bandwidth is wide, the number of CCEs isincreased, the number of times of blind decoding of the downlink controlchannel is increased, and the processing load of the mobile stationdevice is increased.

Thus, a method of reducing the number of times of blind decoding isused. Each mobile station device sets a CCE for which the downlinkcontrol channel is decoded. Specifically, the mobile station device setsa CCE number (hereinafter, referred to as a “starting point index”) fromwhich the downlink control channel starts to be decoded for each CCEaggregation number by a hash function having an input of a mobilestation ID. The mobile station device decodes the downlink controlchannel using a plurality of CCEs from the set starting point index(hereinafter, a space including a plurality of CCEs for which the mobilestation device determines the downlink control channel is referred to asa “mobile station-specific search space (UE-specific search space)”).

The base station device recognizes a mobile station ID of the mobilestation device to which the downlink control channel is allocated,multiplexes the downlink control channel including control data specificto the mobile station device into a CCE within a mobile station-specificspace determined in response to the mobile station ID, and transmits theCCE to the mobile station device. As described above, a method ofreducing the number of times of decoding the downlink control channel inthe mobile station device is used by limiting the CCE for which themobile station device decodes the downlink control channel.

In A-EUTRA, a study has been made to deal with a frequency band, whichis wider than that of EUTRA, and to secure compatibility with EUTRA. Forexample, a wireless communication system including a plurality offrequency bands (a plurality of subbands) by designating a frequencybandwidth of EUTRA as one unit (subband) has been studied.

In A-EUTRA, which is a wireless communication system including aplurality of subbands, a plurality of methods for radio resourceallocation information indicating radio resource allocation of adownlink shared data channel included in a downlink control channel havebeen studied (see Non-Patent Document 2).

For example, a method using the same radio resource allocationinformation as that of EUTRA has been studied (hereinafter, this methodis referred to as “radio resource allocation method 1”). In radioresource allocation method 1, radio resource allocation informationincluded in the downlink control channel corresponds to only within asubband in which the downlink control channel is arranged and indicateswhich PRB pair is allocated to the downlink shared data channel of themobile station device to which the downlink control channel is allocatedwithin a subband in which the downlink control channel is arranged.Radio resource allocation method 1 can reduce design and operation testloads of the mobile station device since the same radio resourceallocation information as that of EUTRA is used.

Another method of adding subband information to radio resourceallocation information of EUTRA has been studied (hereinafter, thismethod is referred to as “radio resource allocation method 2”). In radioresource allocation method 2, radio resource allocation informationincluded in the downlink control channel is constituted by informationindicating which PRB pair within a single subband is allocated to thedownlink shared data channel of the mobile station device to which thedownlink control channel is allocated and information indicating whichsubband corresponds to the PRB pair.

Since radio resource allocation method 2 requires a new control dataformat including subband information as compared to radio resourceallocation method 1, design and operation test loads of the mobilestation device are slightly increased. However, it is possible toincrease a degree of freedom of scheduling of the base station devicesince a PRB pair of the downlink shared data channel indicated by theradio resource allocation information of the downlink control channel isnot limited to a subband in which the downlink control channel isarranged.

-   Non-Patent Document 1: 3GPP TSG RAN1 #53, Kansas City, USA, 5-9 May,    2008, R1-081948 “Proposals for LTE-Advanced Technologies”-   Non-Patent Document 2: 3GPP TSG RAN1 #53 bis, Warsaw, Poland, Jun.    30-Jul. 4, 2008, R1-082468 “Carrier aggregation in LTE-Advanced”

DISCLOSURE OF INVENTION Problem to be Solved by the Invention

However, if the base station in which radio resource allocation method 1or 2 is applied to A-EUTRA simultaneously allocates PRB pairs of aplurality of subbands to a downlink shared data channel of 1 mobilestation device using radio resource allocation method 1 or 2, it isnecessary to use a plurality of downlink control channels includingmobile station device-specific control data. For example, it isnecessary to simultaneously allocate a large number of PRB pairs to amobile station device for which high-speed, large-volume datacommunication is necessary.

If the base station device simultaneously allocates PRB pairs to onemobile station device over a plurality of subbands using radio resourceallocation method 1 or 2, it is necessary to use a plurality of downlinkcontrol channels.

High-speed, large-volume data communication may be performed using aplurality of downlink control channels as described above. Accordingly,it is necessary to detect a large number of downlink control channelsaddressed to its own mobile station device. A large number of detecteddownlink control channels are combined and decoded. This means that themobile station device should perform blind decoding a large number oftimes. There is a problem in that processing of blind decoding a largenumber of times results in an increase of the processing load of themobile station device.

Means for Solving the Problem

A wireless communication system according to an aspect of the presentinvention includes a plurality of mobile station devices and a basestation device that transmits a transmission signal, including a controlchannel in which one or more control channel elements respectivelyincluding a plurality of time/frequency resources are included, to themobile station devices, wherein the base station device includes: acontrol information generating section which generates controlinformation specific to the mobile station devices; a controlinformation count indicator generating section which generates a controlinformation count indicator indicating the number of pieces of controlinformation of each mobile station device generated by the controlinformation generating section for each mobile station device; and atransmitting section which transmits the control information countindicator generated by the control information count indicatorgenerating section to the mobile station device using one or morecontrol channel elements, and transmits one or more pieces of controlinformation generated by the control information generating section tothe mobile station device using one or more control channels, and themobile station device includes: a receiving section which receives acontrol information count indicator and control information transmittedfrom the base station device within a mobile station-specific searchspace selected based on a mobile station ID of the mobile stationdevice; a control information count indicator detecting section whichdetects the control information indicator received by the receivingsection; and a control channel decoding section which decodes thecontrol channel in response to the number of pieces of controlinformation detected by the control information count indicatordetecting section.

In the aspect of the present invention, the control channel decodingsection may check the control information count indicator detected bythe control information count indicator detecting section, may decodethe control channel until control information pieces of the mobilestation device whose number is indicated are detected if the controlinformation count indicator indicates the number of pieces of controlinformation that is one or more, and may not decode the control channelif the control information count indicator is absent or if the controlinformation specific to the mobile station device is absent.

In the aspect of the present invention, the control information countindicator may indicate the number of pieces of control informationspecific to the mobile station device in a time domain frame in whichthe control information count indicator is arranged.

In the aspect of the present invention, the control channel may bearranged in a control channel element subsequent to a control channelelement in which the control information count indicator is arranged forcontrol channel elements of a predetermined order.

In the aspect of the present invention, the control channel decodingsection may control the number of control channel elements of the mobilestation-specific search space for which the control channel is decodedin response to the number of pieces of control information detected bythe control information count indicator detecting section.

In the aspect of the present invention, the control information countindicator may be preferentially arranged in the control channel elementfirst searched for within the mobile station-specific search spaceselected based on the mobile station ID.

In the aspect of the present invention, the control information countindicator may be arranged in a predetermined number of control channelelements; and the control information count indicator detecting sectionmay detect the control information count indicator in a unit of thepredetermined number of control channel elements.

In the aspect of the present invention, the control information countindicator may further include control information specific to the mobilestation device and includes the number of control channel elementsconstituting one or more control channels; and the control channeldecoding section may check the number of control channel elementsindicated in the control information count indicator and may decode thecontrol channel until control information pieces whose number isindicated in the control information count indicator are detected forone or more control channels constituted by control channel elementswhose number is indicated in the control information count indicator.

In the aspect of the present invention, the base station device mayconfigure a plurality of frequency bands from a plurality of continuoussubcarriers, configures a control channel element from a plurality oftime/frequency resources of a frequency band, and configures a controlchannel from one or more control channel elements; the controlinformation count indicator may indicate the number of pieces of controlinformation specific to the mobile station device for each frequencyband; and the control channel decoding section may decode controlchannels whose number corresponds to the number of pieces of controlinformation detected by the control information count indicatordetecting section for each frequency band.

In the aspect of the present invention, a mobile station device, whichreceives a transmission signal, includes a control channel in which oneor more control channel elements respectively including a plurality oftime/frequency resources are included, transmitted from a base station,the mobile station device including: a receiving section which receivesa transmission signal including the control channel transmitted from thebase station device within a mobile station-specific search spaceselected based on a mobile station ID of the mobile station device; acontrol information count indicator detecting section which detects thecontrol information indicator indicating the number of pieces of controlinformation specific to the mobile station device received by thereceiving section; and a control channel decoding section which decodesthe control channel in response to the number of pieces of controlinformation detected by the control information count indicatordetecting section.

In the aspect of the present invention, the control channel decodingsection may check the control information count indicator detected bythe control information count indicator detecting section, may decodethe control channel until control information pieces of the mobilestation device whose number is indicated are detected if the controlinformation count indicator indicates the number of pieces of controlinformation that is one or more, and may not decode the control channelif the control information count indicator is absent or if the controlinformation specific to the mobile station device is absent.

In the aspect of the present invention, the control information countindicator may indicate the number of pieces of control informationspecific to the mobile station device in a time domain frame in whichthe control information count indicator is arranged; and the controlchannel decoding section may decode the control channel in response tothe number of pieces of control information detected by the controlinformation count indicator detecting section.

In the aspect of the present invention, the control channel may bearranged in a control channel element subsequent to a control channelelement in which the control information count indicator is arranged forcontrol channel elements of a predetermined order; and the controlchannel decoding section may decode the control channel in response tothe number of pieces of control information detected by the controlinformation count indicator detecting section.

In the aspect of the present invention, the control channel decodingsection may control the number of control channel elements for which thecontrol channel is decoded in response to the number of pieces ofcontrol information detected by the control information count indicatordetecting section.

In the aspect of the present invention, the control information countindicator may be preferentially arranged in the control channel elementfirst searched for within the mobile station-specific search spaceselected based on the mobile station ID; and the control channeldecoding section may decode the control channel in response to thenumber of pieces of control information detected by the controlinformation count indicator detecting section.

In the aspect of the present invention, the control information countindicator may be arranged in a predetermined number of control channelelements; and the control information count indicator detecting sectionmay detect the control information count indicator in a unit of thepredetermined number of control channel elements.

In the aspect of the present invention, the control information countindicator may further include control information specific to the mobilestation device and include the number of control channel elementsconstituting one or more control channels; and the control channeldecoding section may check the number of control channel elementsindicated in the control information count indicator and decode thecontrol channel until control information pieces whose number isindicated in the control information count indicator are detected forone or more control channels constituted by control channel elementswhose number is indicated in the control information count indicator.

In the aspect of the present invention, in the mobile station devicethat receives a transmission signal including the control channeltransmitted from the base station device, which configures a pluralityof frequency bands from a plurality of continuous subcarriers,configures a control channel element from a plurality of time/frequencyresources of a frequency band, and configures a control channel from oneor more control channel elements, the control information countindicator may indicate the number of pieces of control informationspecific to the mobile station device for each frequency band; and thecontrol channel decoding section may decode control channels whosenumber corresponds to the number of pieces of control informationdetected by the control information count indicator detecting sectionfor each frequency band.

A base station device according to still another aspect of the presentinvention that transmits a transmission signal, includes a controlchannel in which one or more control channel elements respectivelyincluding a plurality of time/frequency resources are included, tomobile station devices, the base station device including: a controlinformation generating section which generates control informationspecific to the mobile station devices; a control information countindicator generating section which generates a control information countindicator indicating the number of pieces of control information of eachmobile station device generated by the control information generatingsection for each mobile station device; and a transmitting section whichtransmits the control information count indicator generated by thecontrol information count indicator generating section to the mobilestation device using one or more control channel elements, and transmitsone or more pieces of control information generated by the controlinformation generating section to the mobile station device using one ormore control channels.

Effect of the Invention

According to the present invention, there is an advantageous effect inthat a processing load of decoding to be performed by a mobile stationdevice to detect a plurality of downlink control channels is reduced ina situation where the plurality of downlink control channels areallocated to one mobile station device so as to perform high-speed,large-volume data communication.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a diagram showing a schematic configuration of a radio frameof a downlink radio frame according to an embodiment of the presentinvention.

FIG. 2 is a diagram illustrating a logical relationship between CCEs anda downlink control channel of this embodiment.

FIG. 3 is a diagram illustrating an arrangement example of a resourceelement group in a downlink subframe of this embodiment

FIG. 4 is a diagram illustrating numbering of CCEs within a system bandaccording to a first embodiment of the present invention.

FIG. 5A is a diagram illustrating a radio resource allocation method ofa downlink shared data channel according to the first embodiment of thepresent invention.

FIG. 5B is a diagram illustrating a radio resource allocation method ofa downlink shared data channel according to the first embodiment of thepresent invention.

FIG. 5C is a diagram illustrating a radio resource allocation method ofa downlink shared data channel according to the first embodiment of thepresent invention.

FIG. 5D is a diagram illustrating a radio resource allocation method ofa downlink shared data channel according to the first embodiment of thepresent invention.

FIG. 6 is a schematic block diagram showing a configuration of a basestation device according to the first embodiment.

FIG. 7 is a schematic block diagram showing an internal configuration ofa transmission processing section of a base station according to thefirst embodiment of the present invention.

FIG. 8 is a schematic block diagram showing a configuration of a mobilestation device according to the first embodiment of the presentinvention.

FIG. 9 is a schematic block diagram showing an internal configuration ofa reception processing section of a mobile station according to thefirst embodiment of the present invention.

FIG. 10 is a flowchart showing processing of multiplexing a controlinformation count indicator and one or more downlink control channels inthe first embodiment of the present invention.

FIG. 11 is a flowchart showing processing of detecting a controlinformation count indicator and one or more downlink control channels inthe first embodiment of the present invention.

FIG. 12 is a schematic block diagram showing an internal configurationof a transmission processing section of a base station according to asecond embodiment of the present invention.

FIG. 13 is a schematic block diagram showing an internal configurationof a reception processing section of a mobile station according to thesecond embodiment of the present invention.

FIG. 14 is a diagram illustrating numbering of CCEs within a system bandaccording to the second embodiment of the present invention.

FIG. 15 is a diagram showing a schematic configuration of a downlinkradio frame in EUTRA.

FIG. 16 is a diagram illustrating a logical relationship between CCEsand a downlink control channel in EUTRA.

FIG. 17 is a diagram illustrating an arrangement example of resourceelement groups in a downlink subframe in EUTRA.

BRIEF DESCRIPTION OF THE DRAWINGS

A plurality of embodiments of the present invention will now bedescribed with reference to the drawings. In this embodiment, a wirelesscommunication system includes a base station device 1 and a plurality ofmobile station devices 2. The mobile station devices 2 include both amobile station device corresponding to A-EUTRA and a mobile stationdevice corresponding to only EUTRA.

FIG. 1 is a diagram showing a schematic configuration of a downlinkradio frame of a link from a base station device 1 to a mobile stationdevice 2 according to the present embodiment. In FIG. 1, the horizontalaxis represents a frequency domain and the vertical axis represents atime domain. The downlink radio frame includes PRB pairs including afrequency band and a time band having predetermined widths, and one PRBpair includes 2 PRBs continuous in the time domain.

One PRB includes 12 subcarriers in the frequency domain and includes 7OFDM symbols in the time domain. A system bandwidth is a communicationbandwidth of a base station device 1, and includes a plurality ofsubband bandwidths. For example, 1 subband includes 100 PRBs. In thetime domain, a slot includes 7 OFDM symbols, a subframe includes 2slots, and a radio frame includes 10 subframes. A unit including 1subcarrier and 1 OFDM symbol is referred to as a resource element. In adownlink radio frame, a plurality of PRBs are arranged in response tothe system bandwidth.

In each subframe, at least a downlink shared data channel used intransmission of information data and a downlink control channel used intransmission of control data (control information) are arranged.Although not shown in FIG. 1, downlink pilot channels used in channelestimation of the downlink shared data channel and the downlink controlchannel are distributed and arranged in a plurality of resourceelements. The case where the downlink control channel is arranged infirst, second, and third OFDM symbols of the subframe, and the downlinkshared data channel is arranged in other OFDM symbols is shown in FIG.1, but the OFDM symbols in which the downlink control channel isarranged can vary in a subframe unit.

Although not shown in FIG. 1, a control format indicator channelindicating the number of OFDM symbols constituting the downlink controlchannel is arranged in a first OFDM symbol. In FIG. 1, the downlinkcontrol channel is arranged in the first, second, and third OFDMsymbols. The downlink control channel may be arranged in only the firstOFDM symbol or may be arranged in first and second OFDM symbols. In thesame OFDM symbol, the downlink control channel and the downlink shareddata channel are not arranged together. In the downlink control channel,a mobile station ID, radio resource allocation information of thedownlink shared data channel, multi-antenna-related information, amodulation scheme, a coding rate, a retransmission parameter, and thelike are arranged.

The downlink control channel is constituted by one or more CCEs (ControlChannel Elements). The CCE is constituted by a plurality of resourceelements. FIG. 2 is a diagram illustrating a logical relationshipbetween CCEs and a downlink control channel of the wirelesscommunication system of the present invention. Here, CCE n indicates aCCE of CCE index n. The CCE index is a CCE identification number.

The downlink control channel is constituted by an aggregation includingone or more CCEs. A CCE aggregation indicating the number of CCEsconstituting the downlink control channel is determined in response to acoding rate and an amount of control data. For example, CCE aggregationn including n CCEs can constitute the downlink control channel by 1 CCE(CCE aggregation 1), can constitute the downlink control channel by 2CCEs (CCE aggregation 2), can constitute the downlink control channel by4 CCEs (CCE aggregation 4), or can constitute the downlink controlchannel by 8 CCEs (CCE aggregation 8).

In this embodiment, the CCE is constituted by a plurality of resourceelement groups (also referred to as mini-CCEs) of the same subband. FIG.3 is a diagram illustrating an arrangement example of resource elementgroups in a downlink subframe according to this embodiment. In FIG. 3,the horizontal axis represents a frequency domain and the vertical axisrepresents a time domain. In the arrangement example of FIG. 3, anexample in which 1 resource element group is constituted by 4 resourceelements and is constituted by adjacent resource elements of thefrequency domain when the downlink control channel is constituted byfirst to third OFDM symbols and downlink pilot channels of 2transmission antennas (transmission antenna 1 and transmission antenna2) are arranged is shown.

If resource elements are denoted by the same reference numeral as thedownlink control channel in FIG. 3, it indicates that the resourceelements belong to the same resource element group. A resource elementgroup is configured by skipping a resource element R1 (a downlink pilotchannel to be transmitted from transmission antenna 1) and a resourceelement R2 (a downlink pilot channel to be transmitted from transmissionantenna 2) in which the downlink pilot channels are arranged.

In FIG. 3, numbering (reference numeral “1”) from a resource elementgroup of a first OFDM symbol having a lowest frequency is performed.Next, a resource element group of a second OFDM symbol having a lowestfrequency is numbered (reference numeral “2”). Next, a resource elementgroup of a third OFDM symbol having a lowest frequency is numbered(reference numeral “3”).

Next, a resource element group is numbered (reference numeral “4”)adjacent in the frequency axis to the resource element group (referencenumeral “2”) in which the second OFDM symbol in which no downlink pilotchannel is arranged is numbered. Next, a resource element group isnumbered (reference numeral “5”) adjacent in the frequency axis to theresource element group (reference numeral “3”) in which the third OFDMsymbol in which no downlink pilot channel is arranged is numbered.

Next, a resource element group is numbered (reference numeral “6”)adjacent in the frequency axis to the resource element group (referencenumeral “1”) in which the first OFDM symbol is numbered. Next, aresource element group is numbered (reference numeral “7”) adjacent inthe frequency axis to the resource element group (reference numeral “2”)in which the second OFDM symbol is numbered. Next, a resource elementgroup is numbered (reference numeral “8”) adjacent in the frequency axisto the resource element group (reference numeral “3”) in which the thirdOFDM symbol is numbered. Likewise, resource element groups of subsequentPRB pairs are also numbered.

According to this embodiment, the CCE is constituted by a plurality ofresource element groups of the same subband constituted as shown in FIG.3. For example, 1 CCE is constituted by 9 different resource elementgroups distributed in the frequency domain and the time domain withinthe subband. Specifically, all resource element groups numbered as shownin FIG. 3 are interleaved using a block interleaver in a resourceelement group unit for the entire subband bandwidth for each subband,and 1 CCE is constituted by 9 resource element groups whose numbers arecontinuous after interleaving.

The number of resource element groups of the subband, that is, thenumber of CCEs, varies with a subband bandwidth, the number of downlinkpilot channels corresponding to the number of transmission antennas ofthe base station device 1 for use in communication, and the number ofOFDM symbols constituting the downlink control channel.

FIRST EMBODIMENT

FIG. 4 is a diagram illustrating numbering of CCEs within a system bandaccording to the first embodiment of the present invention. FIG. 4 showsthe case where 5 subbands are configured within the system band and 20CCEs are configured in each subband. In the frequency domain of FIG. 4,it is assumed that the ascending order of frequency is subband 1<subband2<subband 3<subband 4<subband 5.

First the base station device 1 interleaves resource elements by theabove-described block interleaver in subband 1. The base station device1 numbers CCEs respectively including 9 resource element groups as CCE1, CCE 2, CCE 3, CCE 4, CCE 5, CCE 6, CCE 7, CCE 8, CCE 9, CCE 10, CCE11, CCE 12, CCE 13, CCE 14, CCE 15, CCE 16, CCE 17, CCE 18, CCE 19, andCCE 20 in order of output from the block interleaver.

Subsequently, likewise, CCEs of subband 2 are also numbered as CCE 21 toCCE 40. Continuously, likewise, CCEs of subbands 3, 4, and 5 are alsonumbered.

FIGS. 5A to 5D are diagrams illustrating a method of allocating radioresources of the downlink shared data channel in the first embodiment ofthe present invention. FIG. 5A is a diagram showing a configuration ofradio resource allocation information. The radio resource allocationinformation includes subband indices indicating numbers of subbands inwhich radio resources of the downlink shared data channel are allocatedand a resource block group (hereinafter, referred to as “RBG”) bitmapindicating numbers of PRB pair groups within a subband in which radioresources of the downlink shared data channel are allocated.

FIG. 5B is a diagram illustrating the subband indices of FIG. 5A. InFIG. 5B, the case where 5 subbands (subband 1 to subband 5) areconfigured within a system band is shown. The subband indices storenumbers of subbands in which radio resources of the downlink shared datachannel are allocated within the 5 subbands.

FIG. 5C is a diagram illustrating a configuration of an RBG. The RBG isconstituted by a plurality of PRB pairs, and the number of PRB pairsconstituting 1 RBG is set by the number of PRB pairs within a subbandband. In FIG. 5C, the case where 100 PRB pairs are configured within 1subband band and 1 RBG is constituted by 4 PRB pairs is shown. Forsimplicity of description, in FIG. 5C, only 1 PRB of a PRB pair isshown.

FIG. 5D is a diagram illustrating the RBG bitmap of FIG. 5A. In the RBGbitmap, 1 bit is configured for each RBG index, and a bit correspondingto an RBG index is pre-associated with a bit of a specific positionwithin the RBG bitmap. Each bit indicates whether or not a correspondingRBG is allocated for the downlink shared data channel. For example, whena bit value is “0”, it indicates that a corresponding RBG is notallocated. When a bit value is “1”, it indicates that a correspondingRBG is allocated. The radio resource allocation information as describedabove is included in the downlink control channel.

FIG. 6 is a schematic block diagram showing a configuration of the basestation device 1 according to the first embodiment of the presentinvention. As shown in FIG. 6, the base station device 1 has a radioresource control section 10, a control section 11, a transmissionprocessing section 12, and a reception processing section 13.

The radio resource control section 10 manages radio resource controlinformation including transmission power of each of the mobile stationdevices 2, an intermittent transmission/reception cycle, a transmissioncycle of a channel quality indicator (CQI) signal, and modulationschemes/coding rates of a downlink shared data channel and an uplinkshared data channel, and the like, and transmits the radio resourcecontrol information to the mobile station device 2 through thetransmission processing section 12.

The radio resource control section 10 schedules radio resourceallocation of a downlink control channel directed to the mobile stationdevice 2, determines a coding rate of the downlink control channel, andoutputs information including a mobile station ID of the mobile stationdevice 2 to which radio resources are allocated to the transmissionprocessing section 12 via the control section 11.

The control section 11 determines the number of CCEs (a CCE aggregationnumber) of one or more downlink control channels allocated to the mobilestation device 2 based on information indicating coding rates of one ormore downlink control channels input from the radio resource controlsection 10 for each mobile station device, and outputs relatedinformation to the transmission processing section 12 along with themobile station ID of the mobile station device 2 to which one or moredownlink control channels are allocated.

The control section 11 instructs the transmission processing section 12to generate a control information count indicator indicating the numberof control data (control information) (hereinafter, control data(control information) specific to the mobile station device 2 isreferred to as “mobile station device-specific data”) specific to themobile station device 2 to which one or more downlink control channelsare allocated.

The control section 11 generates mobile station device-specific data tobe transmitted using one or more downlink control channels, and outputsthe mobile station device-specific data to the transmission processingsection 12.

The mobile station device-specific data to be transmitted on eachdownlink control channel includes a mobile station ID, radio resourceallocation information of a downlink shared data channel,multi-antenna-related information, a modulation scheme, a coding rate, aretransmission parameter, information of a CRC (CRC masked by UE ID)code and the like. For the transmission processing section 12, thecontrol section 11 controls radio resource allocation, a modulationscheme, and a coding rate of the downlink shared data channel based oninformation input from the radio resource control section 10.

The transmission processing section 12 generates and transmits one ormore downlink control channels, a downlink shared data channel, and acontrol information count indicator based on control data includingmobile station device-specific data input from the control section 11.The transmission processing section 12 sets a mobile station-specificsearch space of the mobile station device 2 to which one or moredownlink control channels are allocated based on the mobile station ID,multiplexes a control information count indicator addressed to themobile station device 2 into one or more CCEs within the mobilestation-specific search space, multiplexes one or more other downlinkcontrol channels into one or more CCEs within the mobilestation-specific search space, and transmits the CCEs. The number ofCCEs to be used to multiplex the downlink control channel is based oninformation input from the control section 11. The transmissionprocessing section 12 sets a mobile station-specific search space foreach CCE aggregation number based on a mobile station ID and a hashfunction.

The reception processing section 13 extracts control data includingmobile station device-specific data and information data by demodulatingand decoding a reception signal received by a reception antenna from themobile station device 2 according to an instruction of the controlsection 11. The reception processing section 13 outputs the control dataincluding the mobile station device-specific data to the control section11, and outputs the information data to a processing device of an upperlayer (not shown).

FIG. 7 is a schematic block diagram showing an internal configuration ofthe transmission processing section 12 of the base station device 1according to the first embodiment of the present invention. Thetransmission processing section 12 of the base station device 1 has aplurality of downlink shared data channel processing sections 210, aplurality of downlink control channel processing sections (controlinformation generating sections) 220, a CCE aggregation processingsection 250, a plurality of control information count indicatorgenerating sections 260, a pilot channel processing section 240, amultiplexing section 230, an IFFT (Inverse Fast Fourier Transform)section 201, a GI (Guard Interval) inserting section 202, a D/A(Digital/Analog conversion) section 203, and a transmission RF (RadioFrequency) section 204. The IFFT section 201, the GI inserting section202, the D/A section 203, and the transmission RF section 204 arecollectively referred to as a transmitting section 200.

Since the plurality of downlink shared data channel processing sections210, the plurality of downlink control channel processing sections 220,and the plurality of control information count indicator generatingsections 260 have the same configuration and function as each other, onewill be representatively described.

The downlink shared data channel processing section 210 has a turbocoding section 211, a data modulating section 212, and a shared datachannel S/P (Serial/Parallel conversion) section 213. The downlinkcontrol channel processing section 220 has a convolutional codingsection 221, a QPSK (Quadrature Phase Shift Keying) modulation section222, and a control channel S/P section 223.

Each downlink shared data channel processing section 210 performsbaseband processing for transmitting information data directed to eachmobile station device 2 in an OFDM scheme. The downlink shared datachannel processing section 210 also processes control data includinginformation different from that of the downlink control channelprocessing section 220.

According to an instruction of a coding rate from the control section11, the turbo coding section 211 performs turbo coding for improvingerror resilience of information data.

The data modulating section 212 outputs a modulation symbol signalsequence by modulating information data encoded by the turbo codingsection 211 in a modulation scheme instructed from the control section11 among modulation schemes such as QPSK, 16 quadrature amplitudemodulation (16QAM), and 64 quadrature amplitude modulation (64QAM). Theshared data channel S/P section 213 converts a serial signal sequence(stream) output by the data modulating section 212 into parallel signalsequences.

Each downlink control channel processing section 220 performs basebandprocessing for transmitting one or more mobile station device-specificdata specific to the mobile station device 2 including information suchas radio resource allocation information and a mobile station ID in theOFDM scheme.

The convolutional coding section 221 performs convolutional coding forimproving error resilience of the mobile station device-specific dataaccording to an instruction of a coding rate from the control section11. Here, the mobile station device-specific data is expressed in a bitunit, and the convolutional coding section 221 also performs ratematching for adjusting the number of output bits for bits for whichconvolutional coding processing is performed.

The QPSK modulation section 222 outputs a modulation symbol signalsequence by modulating the encoded mobile station device-specific datain the QPSK modulation scheme.

The control channel S/P section 223 converts the serial signal sequenceoutput by the QPSK modulation section 222 into parallel signalsequences.

The CCE aggregation processing section 250 performs rearrangementprocessing for multiplexing signals of the one or more downlink controlchannels output from the control channel S/P section 223 into CCEsaccording to an instruction of the number of CCEs designated from thecontrol section 11. The multiplexing of the signals of the one or moredownlink control channels into the CCEs will be described below indetail.

The CCE aggregation processing section 250 has a block interleaver, andinterleaves downlink control channel signals, which are arranged in CCEsfor each subband, in a resource element group unit. One CCE isconstituted by 9 resource element groups for which interleaving isperformed in the resource element group unit. Respective downlinkcontrol channel signals output by the control channel S/P sections 223are distributed and multiplexed into a plurality of resource elementgroups in the multiplexing section 230 to be described later.

Each of the plurality of control information count indicator generatingsections 260 generates a control information count indicator indicatingthe number of mobile station device-specific data of a plurality ofmobile station devices, that is, the number of downlink control channelssimultaneously allocated to 1 mobile station device 2. The controlinformation count indicator has a different information amount fromvarious control data formats constituting mobile station device-specificdata in the downlink control channel.

The control information count indicator generating section 260 generatesa CRC code using a predetermined generating polynomial for a bitsequence indicating the number of mobile station device-specific data,and performs convolutional coding for information (CRC masked by UE ID)taken by an exclusive OR operation of a mobile station ID of the mobilestation device 2 for which the number of mobile station device-specificdata is indicated using the control information count indicator and thegenerated CRC code and the above-described bit sequence, performs theQPSK modulation, and generates a signal of the control information countindicator. For CCEs designated from the control section 11, the signalof the control information count indicator is multiplexed into aplurality of resource element groups distributed in the multiplexingsection 230 like the above-described CCE aggregation processing section250.

The pilot channel processing section 240 generates a signal of adownlink pilot channel, which is a known signal in the mobile stationdevice 2, and outputs the signal to the multiplexing section 230.

The multiplexing section 230 multiplexes a signal output by the pilotchannel processing section 240, a signal output by the controlinformation count indicator generating section 260, a signal output bythe CCE aggregation processing section 250, and a signal output by thedownlink shared data channel processing section 210 into a downlinkradio frame based on allocation determined by the control section 11. Atthis time, the mobile station ID of the mobile station device 2 to whichthe control information count indicator, the downlink control channel,and the downlink shared data channel are allocated is referred to.

Multiplexing between the downlink shared data channel and the downlinkcontrol channel is performed by time multiplexing as shown in FIG. 1.Multiplexing between the downlink pilot channel and another channel isperformed by time/frequency multiplexing. The control information countindicator and the downlink control channel are multiplexed bytime/frequency multiplexing in a CCE unit. Details of processing of themultiplexing section 230 for multiplexing a control information countindicator and one or more downlink control channels allocated to thesame mobile station device 2 into CCEs will be described in detaillater.

The IFFT section 201 transforms a multiplexed signal from themultiplexing section 230 by an IFFT and modulates the IFFT signal in theOFDM scheme.

The GI inserting section 202 generates a digital baseband signalincluding a symbol of the OFDM scheme by adding a GI to the modulatedsignal of the OFDM scheme by the IFFT section 201. The GI is generatedby reproducing part of a head or tail of a symbol to be transmitted.

The D/A section 203 converts the digital baseband signal input from theGI inserting section 202 into an analog signal.

The transmission RF section 204 generates an in-phase component and aquadrature component of an intermediate frequency from the input analogsignal, removes an extra frequency component from an intermediatefrequency band, converts (up-converts) an intermediate frequency signalinto a high frequency signal, removes an extra frequency component,power-amplifies the high frequency signal, and transmits the signal viaa transmission antenna.

That is, the transmitting section 200 including the IFFT section 201,the GI inserting section 202, the D/A section 203, and the RF section204 transmits a control information count indicator and one or moredownlink control channels multiplexed by the multiplexing section 230into CCEs via the transmission antenna. Since the reception processingsection 13 of the base station device 1 is not related to the presentinvention, detailed description thereof is omitted.

FIG. 8 is a schematic block diagram showing a configuration of themobile station device 2 according to the first embodiment of the presentinvention. As shown in FIG. 8, the mobile station device 2 has a controlsection 20, a reception processing section 21, and a transmissionprocessing section 22.

The reception processing section 21 receives a signal from the basestation device 1, decodes the control information count indicator usinga CCE within a mobile station-specific search space based on the mobilestation ID of its own mobile station device 2 input from the controlsection 20, and detects the number of mobile station device-specificdata addressed to its own mobile station device 2. If the controlinformation count indicator indicating the number of mobile stationdevice-specific data addressed to its own mobile station device 2 isdetected, the downlink control channel is decoded using another CCEwithin the mobile station-specific search space, and downlink controlchannels addressed to its own mobile station device 2 whose number isindicated by the control information count indicator are detected.Details of the detection of the control information count indicator andthe detection of the one or more downlink control channels will bedescribed later.

If the one or more downlink control channels addressed to its own mobilestation device 2 are detected, the reception processing section 21outputs mobile station-specific data acquired from the one or moredownlink control channels to the control section 20. The receptionprocessing section 21 outputs information data acquired by decoding adownlink shared data channel addressed to its own mobile station device2 to a processing device of an upper layer (not shown).

The control section 20 controls the transmission processing section 22and the reception processing section 21 based on control data reportedusing the downlink control channel and the downlink shared data channelfrom the base station device 1. The control section 20 outputs a mobilestation ID previously allocated from the base station device 1 to thereception processing section 21.

Specifically, at an initial communication connection time, the mobilestation device 2 communicates with the base station device 1. Duringthis procedure, the mobile station ID is reported from the base stationdevice 1 to the mobile station device 2.

According to an instruction of the control section 20, the transmissionprocessing section 22 encodes information data and control data andtransmits a modulated signal to the base station device 1 via atransmission antenna.

FIG. 9 is a schematic block diagram showing an internal configuration ofthe reception processing section 21 of the mobile station device 2according to the first embodiment of the present invention. Thereception processing section 21 of the mobile station device 2 has areception RF section 301, an A/D (Analog/Digital conversion) section302, a symbol timing detecting section 303, a GI removing section 304,an FFT section 305, a demultiplexing section 320, a channel estimatingsection 340, channel compensation sections 330 (for downlink shared datachannels), a P/S (Parallel/Serial conversion) section 350, a datademodulating section 380, a turbo decoding section 390, a channelcompensation section 360 (for a control information count indicator anda downlink control channel), a starting CCE selecting section 410, a CCEreconfiguration section 370, a control information count indicatordetecting section 400, a CCE selecting section 311, a QPSK demodulationsection 312, a Viterbi decoder section 313, and a CRC inspection section314. The CCE selecting section 311, the QPSK demodulation section 312,the Viterbi decoder section 313, and the CRC inspection section 314 arecollectively referred to as a control channel decoding section 310. Thereception RF section 301, the A/D section 302, the GI removing section304, the FFT section 305, and the symbol timing detecting section 303are collectively referred to as a receiving section 300.

The reception RF section 301 appropriately amplifies a signal receivedby the reception antenna, converts (down-converts) the amplified signalinto an intermediate frequency, removes an unnecessary frequencycomponent, controls an amplification level to appropriately maintain asignal level, and performs quadrature demodulation based on an in-phasecomponent and a quadrature component of the received signal.

The A/D section 302 converts a quadrature-demodulated analog signal intoa digital signal. The symbol timing detecting section 303 detects atiming of a symbol boundary based on the digital signal output by theA/D section 302, and outputs a control signal indicating the detectedtiming of the symbol boundary.

The GI removing section 304 removes a part corresponding to a GI fromthe digital signal output from the A/D section 302 based on the controlsignal from the symbol timing detecting section 303, and outputs theremaining signal. The FFT section 305 transforms the signal output fromthe GI removing section 304 by an FFT, and performs demodulation of theOFDM scheme.

That is, the receiving section 300 including the reception RF section301, the A/D section 302, the GI removing section 304, the FFT section305, and the symbol timing detecting section 303 receives a signal fromthe base station device 1 via the reception antenna.

Based on an instruction from the control section 20, the demultiplexingsection 320 separates demodulated signals from the FFT section 305 intoa signal of a time/frequency domain where a downlink control channel anda control information count indicator are arranged and a signal of atime/frequency domain where a downlink shared data channel is arranged,and outputs the signals to the channel compensation section 360 and thechannel compensation section 330.

In detail, the demultiplexing section 320 outputs signals of resourceelements (constituting CCEs) in which the control information countindicator and the downlink control channel are arranged to the channelcompensation section 360, and outputs signals of resource elements inwhich the downlink shared data channel is arranged to the channelcompensation section 330. Although not described here, the controlsection 20 controls the demultiplexing section 320 based on the numberof OFDM symbols of the downlink control channel indicated in a receivedcontrol format indicator channel. The control information countindicator and the downlink control channel are multiplexed into the sameOFDM symbols.

The channel estimating section 340 estimates a channel state using areceived reference signal (a downlink pilot channel) (not shown) and aspecified value of a reference signal upon transmission (pre-reported tothe mobile station device 2), and outputs a control signal for adjustingan amplitude and a phase so as to compensate for channel fluctuation.This control signal is output for each subcarrier. Although not shown,the demultiplexing section 320 separates resource elements in which thedownlink pilot channel is arranged, and outputs the separated resourceelements to the channel estimating section 340.

The channel compensation section 330 adjusts amplitudes and phases ofsignals of resource elements in which the downlink shared data channelseparated by the demultiplexing section 320 is arranged for eachsubcarrier according to a control signal from the channel estimatingsection 340.

The P/S section 350 converts parallel signal sequences adjusted by thechannel compensation section 330 into a serial signal sequence.

The data demodulating section 380 demodulates a signal of the downlinkshared data channel converted by the P/S section 350. This demodulationcorresponds to a modulation scheme used in the data modulating section212 of the base station device 1. When a chase combining method is usedas hybrid automatic repeat request (HARQ), the data demodulating section380 combines an error-detected data channel with a retransmitted datachannel.

The turbo decoding section 390 decodes information data from thedownlink shared data channel demodulated by the data demodulatingsection 380. When an incremental redundancy method is used as HARQ, theturbo decoding section 390 decodes a combination of an error-detecteddownlink shared data channel and a retransmitted downlink shared datachannel.

The channel compensation section 360 adjusts amplitudes and phases ofsignals of resource elements (CCEs) in which the control informationcount indicator and the downlink control channel separated by thedemultiplexing section 320 are arranged according to information fromthe channel estimating section 340.

Based on a hash function having an input of a mobile station ID inputfrom the control section 20, the starting CCE selecting section 410selects a starting point index of a CCE in which the control informationcount indicator is started to be detected.

The starting CCE selecting section 410 outputs a starting point index ofCCEs selected for each CCE aggregation number and a mobilestation-specific search space determined in response to the mobilestation ID to the control information count indicator detecting section400.

The CCE reconfiguration section 370 includes a block deinterleaver,which performs the inverse processing of the interleaving processingthat is performed by the block interleaver of the base station device 1,and performs interleaving in a resource element group unit within aselected subband. The CCE reconfiguration section 370 reconfigures 1 CCEfrom 9 resource element groups having continuous numbers for whichdeinterleaving is performed, and outputs all CCEs to the controlinformation count indicator detecting section 400 and the CCE selectingsection 311 in ascending order of numbers.

The control information count indicator detecting section 400 detects acontrol information count indicator in a CCE within a mobilestation-specific search space based on the starting point index of CCEsinput from the starting CCE selecting section 410 and the mobilestation-specific search space for the CCEs input from the CCEreconfiguration section 370.

The control information count indicator detecting section 400 detectsthe control information count indicator in a CCE unit of a CCEaggregation number. The control information count indicator detectingsection 400 performs QPSK modulation for signals arranged in the CCEs,and performs Viterbi decoding for the QPSK-modulated signals. Thecontrol information count indicator detecting section 400 performs theViterbi decoding at a fixed coding rate for each CCE aggregation number.

Next, the control information count indicator detecting section 400performs CRC (CRC masked by UE ID) check for a Viterbi-decoded bitsequence using the mobile station ID.

Next, if no error is detected by the CRC (CRC masked by UE ID) check,the control information count indicator detecting section 400 determinesthe number of mobile station device-specific data addressed to its ownmobile station device 2 by checking a bit sequence from which a CRC codeis removed. If a control information count indicator addressed to itsown mobile station device 2 is detected, the control information countindicator detecting section 400 outputs a control signal of aninstruction for starting processing to the CCE selecting section 311along with a CCE number in which the control information count indicatoris detected, information indicating a CCE range of the mobilestation-specific search space, and information indicating the number ofmobile station device-specific data addressed to its own mobile stationdevice 2.

If no error is detected by the CRC check, but a bit sequence from whichthe CRC code is removed is an unexpected sequence, that is, a sequencenot predefined by the wireless communication system, the controlinformation count indicator detecting section 400 continuously detects acontrol information count indicator in another CCE within the mobilestation-specific search space without determining that the controlinformation count indicator addressed to its own mobile station device 2is detected.

If an error is detected by the CRC check, the control information countindicator detecting section 400 continuously detects the controlinformation count indicator in another CCE within the mobilestation-specific search space.

Furthermore, if no control information count indicator is detectedwithin the mobile station-specific search space of the CCE aggregationnumber in which the detection of the control information count indicatoris performed, the detection of the control information count indicatoris performed for CCEs of the next CCE aggregation number.

If a control signal indicating the start of processing is input from thecontrol information count indicator detecting section 400, the CCEselecting section 311 starts to process CCEs.

If a control signal indicating the start of processing is not input fromthe control information count indicator detecting section 400, the CCEselecting section 311 does not process CCEs.

If a control signal indicating the start of processing is input from thecontrol information count indicator detecting section 400, the CCEselecting section 311 outputs signals arranged in CCEs to the QPSKdemodulation section 312 by selecting candidate CCEs in which downlinkcontrol channels whose number is indicated by the control informationcount indicator detecting section 400 are arranged based on CCE numbersin which the control information count indicator input from the controlinformation count indicator detecting section 400 is detected for CCEsinput from the CCE reconfiguration section 370 and a CCE range of themobile station-specific search space. The CCE selecting section 311outputs the signals arranged in the CCEs to the QPSK demodulationsection 312 in a CCE unit of a CCE aggregation number.

Until the rear-stage processing section detects mobile stationdevice-specific data (control information) whose number is indicated bythe control information count indicator detecting section 400 includedin a downlink control channel addressed to its own mobile station device2, the CCE selecting section 311 outputs signals of CCEs within themobile station-specific search space to the QPSK demodulation section312, and detection information of the mobile station device-specificdata included in the downlink control channel addressed to its ownmobile station device 2 is input from the control section 20. Details ofa CCE in which the control information count indicator is arranged andCCEs in which one or more downlink control channels including the mobilestation device-specific data are arranged will be described later.

The QPSK demodulation section 312 performs QPSK demodulation for signalsarranged in candidate CCEs in which one or more downlink controlchannels addressed to its own mobile station device 2 are arranged, andinput from the CCE selecting section 311.

The Viterbi decoder section 313 decodes a signal demodulated by the QPSKdemodulation section 312 based on a coding rate input from the controlsection 20. Here, the signal is expressed in a bit unit, and the Viterbidecoder section 313 performs rate matching for adjusting the number ofbits in which Viterbi decoding processing is performed for input bitsaccording to an instruction of the coding rate from the control section20.

The CRC inspection section 314 performs CRC check for a bit sequencedecoded by the Viterbi decoder section 313. In a state in which no erroris detected by the CRC check, the CRC inspection section 314 recognizesthat a bit sequence passing through the check is mobile stationdevice-specific data addressed to its own mobile station device 2received without an error, and outputs the mobile stationdevice-specific data to the control section 20.

If the control information count indicator is detected as describedabove, processing for the downlink control channel is performed for CCEswithin the mobile station-specific search space within a downlinksubframe from which the control information count indicator is detected.If the mobile station device-specific data addressed to its own mobilestation device 2 included in downlink control channels whose number isindicated in the control information count indicator is detected, themobile station device 2 terminates the decoding of the downlink controlchannels.

The control section 20 receiving information included within the mobilestation device-specific data of the one or more downlink controlchannels detected as described above, for example, one or more pieces ofradio resource allocation information of the downlink shared datachannel, instructs the demultiplexing section 320, the data demodulatingsection 380, and the turbo decoding section 390 to perform receptionprocessing for the downlink shared data channel addressed to the mobilestation device 2.

The mobile station ID is arranged as information combined with a CRCcode for error detection among mobile station device-specific data. Forexample, the CRC code is generated from the mobile stationdevice-specific data using a predetermined generating polynomial, andinformation taken by an exclusive OR operation with the mobile stationID of the mobile station device 2 serving as a destination of the mobilestation device-specific data is arranged within the downlink controlchannel.

The CRC inspection section 314 determines whether or not it is themobile station device-specific data addressed to its own mobile stationdevice 2 along with error detection by performing the inverse processingof the above-described operation for the mobile station device-specificdata using the mobile station ID of its own mobile station device 2.

The control section 20 controls the data demodulation section 380, theturbo decoding section 390, the demultiplexing section 320, and thetransmission processing section 22 based on one or more mobile stationdevice-specific data output by the CRC inspection section 314. Themobile station device-specific data includes radio resource allocationinformation, a modulation scheme/coding rate, a retransmissionparameter, and the like. The control section 20 outputs informationindicating that the mobile station device-specific data is input fromthe CRC inspection section 314 to the CCE selecting section 311. Sincethe transmission processing section 22 of the mobile station device 2 isnot related to the present invention, detailed description thereof isomitted.

Next, an arrangement of one or more downlink control channels addressedto the mobile station device 2, which are the same as those of thecontrol information count indicator, in CCEs will be described indetail.

The multiplexing section 230 of the base station device 1 multiplexes acontrol information count indicator into any CCE within the mobilestation-specific search space of the mobile station device 2 to whichthe downlink control channel is allocated. Next, the multiplexingsection 230 of the base station device 1 multiplexes downlink controlchannels whose number is indicated by the control information countindicator into CCEs within the mobile station-specific search space,which are CCEs having numbers next and subsequent to the CCE into whichthe control information count indicator is multiplexed. The multiplexingsection 230 multiplexes the control information count indicator usingCCEs whose number is the same as a CCE aggregation number of thedownlink control channel. That is, if the downlink control channel isallocated using 2 CCEs, the control information count indicator is alsogenerated and multiplexed so that it is multiplexed into 2 CCEs.

The control information count indicator detecting section 400 of themobile station device 2 detects the control information count indicatorfrom a CCE within the mobile station-specific search space for each CCEaggregation number. If the control information count indicator isdetected, the control information count indicator detecting section 400inputs information indicating a CCE aggregation number from which thecontrol information count indicator is detected to the CCE selectingsection 311. The CCE selecting section 311 of the mobile station device2 sequentially selects CCEs within the mobile station-specific searchspace, which are CCEs having numbers next and subsequent to a CCE intowhich the control information count indicator is multiplexed by the CCEaggregation number, and outputs the selected CCEs to the QPSKdemodulation section 312 until downlink control channels whose number isindicated by the control information count indicator including mobilestation device-specific data addressed to its own mobile station device2 are detected.

An example will be described using FIG. 4. Here, the case where the CCEaggregation number is 2, the number of CCEs constituting the mobilestation-specific search space is 10, and a starting point index of CCEsis CCE 31 (belonging to subband 2) will be described.

The multiplexing section 230 of the base station device 1 multiplexes acontrol information count indicator into 2 CCEs of CCE 33 and CCE 34,and multiplexes downlink control channels into 2 CCEs of CCE 37 and CCE38 and 2 CCEs of CCE 39 and CCE 40. Here, the control information countindicator indicates that 2 downlink control channels are allocated tothe same mobile station device 2.

The control information count indicator detecting section 400 of themobile station device 2 selects the mobile station-specific search spaceof the case where a CCE aggregation number is 2, starts to detect thecontrol information count indicator from a CCE of CCE 31, and detectsthe control information count indicator in 2 CCEs of CCE 33 and CCE 34.The control information count indicator detecting section 400 of themobile station device 2 recognizes that 2 downlink control channels areallocated to its own mobile station device 2 from the controlinformation count indicator, and outputs its information to the CCEselecting section 311.

The CCE selecting section 311 of the mobile station device 2 outputs 2unit CCEs from a CCE of CCE 35 to the rear-stage processing section. Inthe rear-stage processing section, processing of decoding the downlinkcontrol channels is performed by assuming a plurality of types ofcontrol data formats having different information amounts. The mobilestation device 2 detects the downlink control channels addressed to itsown mobile station device 2 in 2 CCEs of CCE 37 and CCE 38 and 2 CCEs ofCCE 39 and CCE 40, and terminates decoding processing for the downlinkcontrol channels.

The control section 20 of the mobile station device 2 outputs detectioninformation of the downlink control channels addressed to its own mobilestation device 2 to the CCE selecting section 311. The CCE selectingsection 311 compares the number of downlink control channels detected bythe rear-stage processing section input from the control section 20 witha number indicated from the control information count indicatordetecting section 400, and stops a signal output if it is determinedthat all downlink control channels whose number is indicated aredetected.

If the control information count indicator is not detected in the mobilestation-specific search space when the CCE aggregation number is 2, thecontrol information count indicator detecting section 400 of the mobilestation device 2 equally performs the detection of the controlinformation count indicator even in the mobile station-specific searchspace when the CCE aggregation number is 1, 4, and 8.

The control information count indicator detecting section 400 of themobile station device 2 may start to detect the control informationcount indicator from any CCE aggregation number. If the controlinformation count indicator is detected, the control information countindicator detecting section 400 of the mobile station device 2 does notperform processing of detecting the control information count indicatorin other CCE aggregation numbers.

FIG. 10 is a flowchart showing processing of multiplexing a controlinformation count indicator and one or more downlink control channels inthe transmission processing section 22 of the base station device 1.

First, the transmission processing section 22 of the base station device1 selects a starting point index based on a mobile station ID of themobile station device 2 to which the downlink control channel isallocated (step S101). Next, the transmission processing section 22 ofthe base station device 1 multiplexes the control information countindicator into a CCE within the mobile station-specific search spacebased on the selected starting point index (step S102). Next, thetransmission processing section 22 of the base station device 1multiplexes one or more downlink control channels into other CCEs withinthe mobile station-specific search space (step S103).

FIG. 11 is a flowchart showing processing of detecting a controlinformation count indicator and one or more downlink control channels inthe reception processing section 21 of the mobile station device 2.

First, the reception processing section 21 of the mobile station device2 selects a starting point index based on a mobile station ID of its ownmobile station device 2 (step S201). Next, the reception processingsection 21 of the mobile station device 2 detects the controlinformation count indicator using a CCE within the mobilestation-specific search space based on the selected starting point index(step S202). Next, the reception processing section 21 of the mobilestation device 2 determines whether or not the control information countindicator is detected (step S203).

If no control information count indicator is detected in step S203, thereception processing section 21 of the mobile station device 2 furtherdetermines whether or not the processing of detecting the controlinformation count indicator is performed for all CCEs within the mobilestation-specific search space (step S204).

If it is determined that the processing of detecting the controlinformation count indicator is not performed for all CCEs within themobile station-specific search space in step S204, the receptionprocessing section 21 of the mobile station device 2 returns to stepS202 to perform the processing of detecting the control informationcount indicator using CCEs for which the processing of detecting thecontrol information count indicator is not yet performed. If it isdetermined that the processing of detecting the control informationcount indicator is performed for all CCEs within the mobilestation-specific search space in step S204, the reception processingsection 21 of the mobile station device 2 terminates the processing.

If the control information count indicator is detected in step S203, thereception processing section 21 of the mobile station device 2 detectsone or more downlink control channels using other CCEs within the mobilestation-specific search space (step S205). Next, the receptionprocessing section 21 of the mobile station device 2 determines whetheror not downlink control channels whose number is indicated in thecontrol information count indicator addressed to its own mobile stationdevice 2 are detected (step S206).

If it is determined that the downlink control channels whose number isindicated in the control information count indicator addressed to itsown mobile station device 2 are detected in step S206, the receptionprocessing section 21 of the mobile station device 2 terminates theprocessing. If it is determined that the downlink control channels whosenumber is indicated in the control information count indicator addressedto its own mobile station device 2 are not detected in step S206, thereception processing section 21 of the mobile station device 2 furtherdetermines whether or not the processing of detecting the downlinkcontrol channels is performed for all other CCEs within the mobilestation-specific search space (step S207).

If it is determined that the processing of detecting the downlinkcontrol channels is performed for all other CCEs within the mobilestation-specific search space in step S207, the reception processingsection 21 of the mobile station device 2 terminates the processing. Ifit is determined that the processing of detecting the downlink controlchannels is not performed for all other CCEs within the mobilestation-specific search space in step S207, the reception processingsection 21 of the mobile station device 2 returns to step S205 tocontinuously detect the downlink control channels using CCEs for whichthe processing of detecting the downlink control channels is not yetperformed.

As described above, the base station device 1 of the first embodiment ofthe present invention transmits a control information count indicatorindicating the number of downlink control channels including mobilestation device-specific data using a CCE within the mobilestation-specific search space, and transmits one or more downlinkcontrol channels including mobile station device-specific data usingother CCEs within the mobile station-specific search space.

The mobile station device 2 of the first embodiment of the presentinvention detects the control information count indicator from a CCEwithin the mobile station-specific search space, and decodes downlinkcontrol channels by assuming a plurality of types of control dataformats having different information amounts for other CCEs within themobile station-specific search space for detecting the downlink controlchannels whose number is indicated in the control information countindicator if the control information count indicator is detected.

Thereby, it is possible to reduce the processing load of decodingdownlink control channels of the mobile station device 2. Particularly,it is preferable that the mobile station device 2 to which no downlinkcontrol channel is allocated perform detection processing by decodingone type of control information count indicator for each CCE aggregationnumber, and it is possible to reduce the processing load of decoding thedownlink control channels.

It is possible to reduce the processing load since the mobile stationdevice 2 does not need to continuously decode downlink control channelsuntil a possible number of downlink control channels are detected foreach downlink subframe using a control information count indicator.

The case where the control information count indicator is QPSK-modulatedlike the downlink control channel and the transmission signal of thecontrol information count indicator is generated by convolutional codinghas been described in the first embodiment, but other signalconfigurations may be used. For example, the QPSK modulation may beperformed without adding the CRC code to a bit sequence indicating thenumber of downlink control channels simultaneously allocated, and it maybe generated by multiplying a scrambling code specific to the mobilestation device 2.

If a correlation value exceeds a predefined threshold value, the mobilestation device 2 may determine that the control information countindicator is detected using a scrambling code of its own mobile stationdevice 2 for a CCE signal, and may perform the QPSK modulation byremoving the multiplied scrambling code from the CCE signal.

BPSK modulation, not the QPSK modulation, may be used.

The case where one or more downlink control channels including mobilestation device-specific data are multiplexed into any CCEs within themobile station-specific search space, which are CCEs having numbers nextand subsequent to that of a CCE into which the control information countindicator is multiplexed, has been described in the first embodiment,but the downlink control channel may be pre-limited to be multiplexedinto a specific CCE. For example, one or more downlink control channelsmay be pre-limited to be multiplexed from CCEs having numbers next tothose of CCEs into which the control information count indicator ismultiplexed.

Thereby, it is possible to reduce the processing load of decodingdownlink control channels of the mobile station device 2.

In response to the number of downlink control channels simultaneouslyallocated, a CCE space (mobile station-specific search area) into whichthe downlink control channel is multiplexed may be controlled.

An example will be described using FIG. 4. Here, the case where a CCEaggregation number is 2, the number of CCEs constituting the mobilestation-specific search space is 10, and a starting point index of CCEsis CCE 25 (belonging to subband 2) will be described.

For example, if 2 downlink control channels are allocated to the mobilestation device 2, the multiplexing section 230 of the base stationdevice 1 multiplexes the 2 downlink control channels respectivelyincluding 2 CCEs into CCEs up to CCE 34.

If the control information count indicator indicates that the 2 downlinkcontrol channels are allocated, the control information count indicatordetecting section 400 of the mobile station device 2 instructs the CCEselecting section 311 to output signals of CCEs up to CCE 34 to therear-stage processing section so as to decode and detect the 2 downlinkcontrol channels respectively including the 2 CCEs. That is, in thiscase, the mobile station-specific search space is not extended.

If 4 downlink control channels are allocated to the mobile stationdevice 2, the multiplexing section 230 of the base station device 1multiplexes the 4 downlink control channels respectively including 2CCEs into CCEs up to CCE 40.

If the control information count indicator indicates that the 4 downlinkcontrol channels are allocated, the control information count indicatordetecting section 400 of the mobile station device 2 instructs the CCEselecting section 311 to output signals of CCEs up to CCE 40 to therear-stage processing section so as to decode and detect the 4 downlinkcontrol channels respectively including the 2 CCEs. That is, in thiscase, the mobile station-specific search space is extended.

The degree of freedom of multiplexing downlink control channels isincreased by adding the processing load of decoding downlink controlchannels to the mobile station device 2 to which many downlink controlchannels are simultaneously allocated.

Thereby, it is possible to control the processing load of decodingdownlink control channels of the mobile station device 2 and the degreeof freedom of multiplexing the downlink control channels in response tothe number of downlink control channels simultaneously allocated.

When a CCE space (mobile station-specific search space) where downlinkcontrol channels are multiplexed is controlled in response to the numberof downlink control channels simultaneously allocated, the number ofCCEs to be controlled for each CCE aggregation number may be different.

The case where the control information count indicator is multiplexedinto any CCE of CCEs within the mobile station-specific search space hasbeen described in the first embodiment, but the control informationcount indicator may be pre-limited to be multiplexed into a specificCCE. For example, the control information count indicator may bepre-limited to be multiplexed into a CCE having a first number withinthe mobile station-specific search space.

Thereby, it is possible to reduce the processing load of detecting thecontrol information count indicator of the mobile station device 2.

The control information count indicator may be multiplexed into only aspecific number of CCE aggregation numbers. That is, the controlinformation count indicator may be arranged in a specific number ofCCEs. For example, if the CCE aggregation number of the downlink controlchannel is CCE aggregation 1 (constituted by 1 CCE), CCE aggregation 2(constituted by 2 CCEs), CCE aggregation 4 (constituted by 4 CCEs), andCCE aggregation 8 (constituted by 8 CCEs), the control information countindicator is set to be multiplexed into only CCE aggregation 1 and CCEaggregation 4.

If one or more downlink control channels constituted by CCE aggregation1 are allocated to the mobile station device 2 or if one or moredownlink control channels constituted by CCE aggregation 2 are allocatedto the mobile station device 2, the control information count indicatoris multiplexed into CCE aggregation 1. If one or more downlink controlchannels constituted by CCE aggregation 4 are allocated to the mobilestation device 2 or if one or more downlink control channels constitutedby CCE aggregation 8 are allocated to the mobile station device 2, thecontrol information count indicator is multiplexed into CCE aggregation4.

If the control information count indicator is detected in CCEaggregation 1, the mobile station device 2 performs processing ofdecoding and detecting one or more downlink control channels allocatedby CCE aggregation 1 and CCE aggregation 2. If the control informationcount indicator is detected in CCE aggregation 4, the mobile stationdevice 2 performs processing of decoding and detecting one or moredownlink control channels allocated by CCE aggregation 4 and CCEaggregation 8.

Information regarding a CCE aggregation number of a downlink controlchannel may be included in the control information count indicator.

Thereby, a limitation that CCE aggregation numbers of the controlinformation count indicator and the downlink control channel should beidentical is removed.

A CCE aggregation number of the control information count indicator,that is, the number of CCEs to be used in multiplexing of 1 controlinformation count indicator, is pre-limited, and the mobile stationdevice 2 may detect the control information count indicator only in alimited CCE aggregation number.

Thereby, the processing load of detecting the control information countindicator of the mobile station device 2 can be reduced.

SECOND EMBODIMENT

The case where information indicating the number of mobile stationdevice-specific data of each subband allocated to the same mobilestation device 2, that is, the number of downlink control channels, isconfigured in a control information count indicator will be described asthe second embodiment of the present invention.

In the second embodiment, functions of a control information countindicator generating section 261 within a transmission processingsection 12 a of a base station device 1 shown in FIG. 12 and a controlinformation count indicator detecting section 401 within a receptionprocessing section 21 a of a mobile station device 2 shown in FIG. 13are different. Since other configurations are identical to those of thefirst embodiment, description thereof is omitted.

The control information count indicator generating section 261 of thebase station device 1 generates a control information count indicatorincluding information indicating the number of downlink control channelsof each subband allocated to the same mobile station device 2. Thenumber of downlink control channels of each subband allocated to thesame mobile station device 2 is designated by the control section 11 ofthe base station device 1.

If a control information count indicator addressed to its own mobilestation device 2 is detected in a CCE within a mobile station-specificsearch space, the control information count indicator detecting section401 of the mobile station device 2 outputs a control signal of aninstruction for starting processing to the CCE selecting section 311along with a CCE number in which the control information count indicatoris detected, information indicating a CCE range of the mobilestation-specific search space, a CCE aggregation number in which thecontrol information count indicator is detected, and informationindicating the number of mobile station device-specific data addressedto its own mobile station device 2 of each subband indicated by thecontrol information count indicator.

The CCE selecting section 311 outputs a CCE signal of each selectedsubband to the rear-stage processing section based on a control signalinput from the control information count indicator detecting section401.

An example of the second embodiment will be described using FIG. 4.Here, the case where the CCE aggregation number is 2, the number of CCEsconstituting the mobile station-specific search space is 10, and astarting point index of CCEs is CCE 31 (belonging to subband 2) will bedescribed.

The control section 11 of the base station device 1 designates signalsof 4 downlink control channels in which a CCE aggregation numberincluding mobile station device-specific data is 2 to be multiplexedinto CCEs of CCE 35 and CCE 36, CCE 51 and CCE 52, CCE 53 and CCE 54,and CCE 95 and CCE 96, and outputs a control signal includinginformation regarding CCEs into which the downlink control channels aremultiplexed to the transmission processing section 22. The controlsection 11 of the base station device 1 designates the controlinformation count indicator to be multiplexed into CCEs of CCE 33 andCCE 34, and outputs a control signal including information regarding theCCEs into which the control information count indicator is multiplexedto the transmission processing section 22.

Based on a control signal input from the control section 11, the controlinformation count indicator generating section 261 of the base stationdevice 1 generates a control information count indicator indicating thatthe number of downlink control channels allocated in subband 1 is 0,that the number of downlink control channels allocated in subband 2 is1, that the number of downlink control channels allocated in subband 3is 2, that the number of downlink control channels allocated in subband4 is 0, and that the number of downlink control channels allocated insubband 5 is 1, and outputs the control information count indicator tothe multiplexing section 230.

The multiplexing section 230 of the base station device 1 multiplexes asignal of a control information count indicator input from the controlinformation count indicator generating section 261 into CCEs of CCE 33and CCE 34, and multiplexes signals of 4 downlink control channelsaddressed to the same mobile station device 2 into CCEs of CCE 35 andCCE 36, CCE 51 and CCE 52, CCE 53 and CCE 54, and CCE 95 and CCE 96.

The control information count indicator detecting section 401 of themobile station device 2 performs processing of detecting a controlinformation count indicator for every 2 CCEs of CCE 31, CCE 32, CCE 33,CCE 34, CCE 35, CCE 36, CCE 37, CCE 38, CCE 39, and CCE 40, which are amobile station-specific search space, and detects the controlinformation count indicator in the CCEs of CCE 33 and CCE 34.

The control information count indicator detecting section 401 detectinga control information count indicator outputs a control signal for aninstruction to start the processing to the CCE selecting section 311along with information indicating that the number of downlink controlchannels allocated in subband 1 is 0, that the number of downlinkcontrol channels allocated in subband 2 is 1, that the number ofdownlink control channels allocated in subband 3 is 2, that the numberof downlink control channels allocated in subband 4 is 0, and that thenumber of downlink control channels allocated in subband 5 is 1,included in the control information count indicator, informationindicating that a CCE in which the control information count indicatoris detected is CCE 33 and CCE 34, information indicating that the mobilestation-specific search space is CCE 31 to CCE 40, and informationindicating that a CCE aggregation number in which the controlinformation count indicator is detected is 2.

Based on a control signal input from the control information countindicator detecting section 401, the CCE selecting section 311 outputssignals of every 2 CCEs of CCE 35 to CCE 40 in subband 2, CCE 51 to CCE60 in subband 3, and CCE 91 to CCE 100 in subband 5 to the rear-stageprocessing section. When signals of CCEs of a subband in which thecontrol information count indicator is detected are output to therear-stage processing section, the CCE selecting section 311 outputssignals of CCEs subsequent to a CCE number in which the controlinformation count indicator is detected within the mobilestation-specific search space to the rear-stage processing section.

If signals of CCEs of a subband in which no control information countindicator is detected are output to the rear-stage processing section,the CCE selecting section 311 outputs signals of CCEs of a subband whosenumbers are relatively identical to those of CCEs of the mobilestation-specific search space to the rear-stage processing section. CCE31 to CCE 40, which are CCEs of the mobile station-specific searchspace, are CCEs whose CCE numbers are 11^(th) to 20^(th) in subband 2.Accordingly, the CCE selecting section 311 outputs signals of CCEs ofCCE 51 to CCE 60, which are CCEs whose CCE numbers are 11^(th) to20^(th) in subband 3, and signals of CCEs of CCE 91 to CCE 100, whichare CCEs whose CCE numbers are 11^(th) to 20^(th) in subband 5, to therear-stage processing section.

As described above, a relationship of CCEs whose orders are identicalbetween different subbands is referred to as a relationship of CCEswhose numbers are relatively identical in the subbands. Via therear-stage processing section, the control section 20 of the mobilestation device 2 acquires mobile station device-specific data includedin 1 downlink control channel addressed to its own mobile station device2 in CCEs of CCE 35 and CCE 36 of subband 2, mobile stationdevice-specific data included in 2 downlink control channel addressed toits own mobile station device 2 in CCEs of CCE 51 and CCE 52 and CCE 53and CCE 54 of subband 3, and mobile station device-specific dataincluded in 1 downlink control channel addressed to its own mobilestation device 2 in CCEs of CCE 95 and CCE 96 of subband 5.

If the mobile station device-specific data included in the downlinkcontrol channel is acquired, the control section 20 outputs informationindicating the subband numbers to which the downlink control channelsbelong to the CCE selecting section 311 along with informationindicating that the mobile station device-specific data is acquired.

If all downlink control channels allocated within the subbands aredetected based on the information input from the control section 20 andthe information input from the control information count indicatordetecting section 401, the CCE selecting section 311 stops an output ofa signal of a CCE in which a downlink control channel is not yet decodedand detected within the subband to the rear-stage processing section.

The mobile station device 2 acquires information data included in adownlink shared data channel based on radio resource allocationinformation of the downlink shared data channel included in mobilestation device-specific data of each acquired downlink control channel.

As described above, the second embodiment of the present inventionincludes information indicating the number of mobile stationdevice-specific data of each subband allocated to the same mobilestation device 2, that is, the number of downlink control channels.Thereby, processing accompanying decoding of a downlink control channelis increased, but it is possible to increase the degree of freedom ofmultiplexing the downlink control channel.

One or more downlink control channels may be multiplexed from a specificCCE without designating a CCE which a signal of a downlink controlchannel is multiplexed within a subband in which a control informationcount indicator is not multiplexed for any CCE of the subband whosenumber is relatively identical to that of a CCE of a mobile stationspecific-search space.

For example, one or more downlink control channels may be multiplexedfrom a CCE whose CCE number is relatively identical to that of a CCEinto which a control information count indicator is multiplexed within asubband in which the control information count indicator is notmultiplexed.

For simplicity of description, an example will be described using FIG. 4described in the second embodiment. If the control information countindicator is multiplexed using 2 CCEs from CCE 33 whose CCE number is13^(th) within subband 2, 2 downlink control channels may be multiplexedusing 4 CCEs from CCE 53 whose number is 13^(th) within subband 3.

One or more downlink control channels may be multiplexed from a CCEwhose CCE number is relatively identical to that of a CCE next to a CCEinto which a control information count indicator is multiplexed in anysubband.

CCE numbering different from that of FIG. 4 may be used. FIG. 14 is adiagram illustrating numbering of CCEs within a system band according tothe second embodiment of the present invention. In FIG. 14, the casewhere 5 subbands are configured within the system band and 20 CCEs areconfigured in each subband is shown. The number of subbands and thenumber of CCEs of FIG. 14 are the same as those of FIG. 4. In thefrequency domain of FIG. 14, it is assumed that the ascending order offrequency is subband 1<subband 2<subband 3<subband 4<subband 5.

First, the base station device 1 interleaves resource elements by theabove-described block interleaver in subband 1. The base station device1 numbers CCEs respectively including 9 resource element groups as CCE1, CCE 2, CCE 3, CCE 4, CCE 5, CCE 6, CCE 7, CCE 8, CCE 9, CCE 10, CCE11, CCE 12, CCE 13, CCE 14, CCE 15, CCE 16, CCE 17, CCE 18, CCE 19, andCCE 20 in order of output from the block interleaver.

Furthermore, subbands are also equally numbered. Numbering is performedas CCE (1, 1), CCE (1, 2), CCE (1, 3), CCE (1, 4), CCE (1, 5), CCE (1,6), CCE (1, 7), CCE (1, 8), CCE (1, 9), CCE (1, 10), CCE (1, 11), CCE(1, 12), CCE (1, 13), CCE (1, 14), CCE (1, 15), CCE (1, 16), CCE (1,17), CCE (1, 18), CCE (1, 19), and CCE (1, 20). Here, for example, inCCE (X, Y), X represents the number of a subband and Y represents thenumber of a CCE within the subband.

Subsequently, likewise, numbering is also performed as CCE (2, 1) to CCE(2, 20) for CCEs of subband 2. Continuously, likewise, numbering is alsoperformed for CCEs of subband 3, subband 4, and subband 5.

An example will be described using FIG. 14. The case where a CCEaggregation number is 2, the number of CCEs constituting a mobilestation-specific search space is 10, and a starting point index of CCEsis CCE (2, 11) (belonging to subband 2) will be described.

The base station device 1 multiplexes signals of 4 downlink controlchannels in which a CCE aggregation number including mobile stationdevice-specific data is 2 into CCEs of CCE (2, 15) and CCE (2, 16), CCE(3, 11) and CCE (3, 12), CCE (3, 13) and CCE (3, 14), and CCE (5, 15)and CCE (5, 16).

The base station device 1 generates a control information countindicator indicating that the number of downlink control channelsallocated in subband 1 is 0, that the number of downlink controlchannels allocated in subband 2 is 1, that the number of downlinkcontrol channels allocated in subband 3 is 2, that the number ofdownlink control channels allocated in subband 4 is 0, and that thenumber of downlink control channels allocated in subband 5 is 1. Thebase station device 1 multiplexes the control information countindicator into CCEs of CCE (2, 13) and CCE (2, 14).

The mobile station device 2 performs processing of detecting a controlinformation count indicator for every 2 CCEs of CCE (2, 11), CCE (2,12), CCE (2, 13), CCE (2, 14), CCE (2, 15), CCE (2, 16), CCE (2, 17),CCE (2, 18), CCE (2, 19), and CCE (2, 20), which are a mobilestation-specific search space, and detects the control information countindicator in the CCEs of CCE (2, 13) and CCE (2, 14).

The mobile station device 2 detecting the control information indicatorselects CCEs of each subband in which processing of decoding a downlinkcontrol channel is performed based on information indicating that thenumber of downlink control channels allocated in subband 1 is 0, thatthe number of downlink control channels allocated in subband 2 is 1,that the number of downlink control channels allocated in subband 3 is2, that the number of downlink control channels allocated in subband 4is 0, and that the number of downlink control channels allocated insubband 5 is 1, included in the control information count indicator,information indicating that the control information count indicator isdetected in CCE (2, 13) and CCE (2, 14), information indicating that themobile station-specific search space is CCE (2, 11) to CCE (2, 20), andinformation that a CCE aggregation number in which the controlinformation count indicator is detected is 2.

The mobile station device 2 decodes a downlink control channel fromsignals of every 2 CCEs of CCE (2, 15) to CCE (2, 20) in subband 2, CCE(3, 11) to CCE (3, 20) in subband 3, and CCE (5, 11) to CCE (5, 20) insubband 5.

If processing of decoding a downlink control channel is performed for aCCE signal of a subband in which a control information count indicatoris detected, the mobile station device 2 performs processing of decodinga downlink control channel from a CCE signal subsequent to a CCE numberin which the control information count indicator is detected within amobile station-specific search space.

If processing of decoding a downlink control channel is performed for aCCE signal of a subband in which a control information count indicatoris not detected, the mobile station device 2 performs processing ofdecoding a downlink control channel for a signal of a CCE of the subbandwhose CCE number is relatively identical to that of a CCE of the mobilestation-specific search space.

The mobile station device 2 detects 1 downlink control channel addressedto its own mobile station device 2 in CCEs of CCE (2, 15) and CCE (2,16) of subband 2, 2 downlink control channels addressed to its ownmobile station device 2 in CCEs of CCE (3, 11) and CCE (3, 12) and CCE(3, 13) and CCE (3, 14) of subband 3, and 1 downlink control channeladdressed to its own mobile station device 2 in CCEs of CCE (5, 15) andCCE (5, 16) of subband 5, and acquires mobile station device-specificdata.

The mobile station device 2 stops processing of decoding a downlinkcontrol channel for CCEs for which processing of decoding and detectinga downlink control channel is not yet performed within a subband if alldownlink control channels are detected within the subband based on thenumber of downlink control channels detected in each subband and thenumber of downlink control channels allocated to each subband indicatedin a control information count indicator.

A program operating in the mobile station device 2 and the base stationdevice 1 according to the present invention is a program that controls aCPU or the like (a program that causes a computer to function) torealize the functions of the devices. Information handled in the devicesis temporarily accumulated in a RAM when the information is processed,is subsequently stored in various ROMs or HDDs, and is read out,amended, and written in by the CPU as necessary.

A recording medium to record the program thereon may be provided as anyone of a semiconductor medium (for example, ROM, nonvolatile memorycard, or the like), an optical recording medium (for example, DVD, MO,MD, CD, BD, or the like), and a magnetic recording medium (for example,magnetic tape, flexible disk, or the like).

By executing the loaded program, the functions of the above embodimentsmay be realized. In addition, processing in cooperation with anoperating system or another application program, or the like based on aninstruction from the program may also realize the functions of thepresent invention.

For market distribution, the program may be recorded on a portablerecording medium to be distributed or may be transferred to a servercomputer connected via a network, such as the Internet. In this case, astorage device of the server computer is also included in the presentinvention.

The embodiments of the present invention have been described in detailwith reference to the drawings. However, specific configurations are notlimited to the embodiments and may include any design in the scopewithout departing from the subject matter of the present invention.

INDUSTRIAL APPLICABILITY

A wireless communication system of the present invention is applicableto a mobile station device and a base station device of a mobilecommunication system such as a mobile phone or the like.

REFERENCE SYMBOLS

-   -   1: Base station device    -   2: Mobile station device    -   10: Radio resource control section    -   11: Control section    -   12, 12 a: Transmission processing section    -   13: Reception processing section    -   20: Control section    -   21, 21 a: Reception processing section    -   22: Transmission processing section    -   200: Transmitting section    -   201: IFFT section    -   202: GI inserting section    -   203: D/A section    -   204: Transmission RF section    -   210: Downlink shared data channel processing section    -   211: Turbo decoding section    -   212: Data modulating section    -   213: Shared data channel S/P section    -   220: Downlink control channel processing section    -   221: Convolutional coding section    -   222: QPSK modulation section    -   223: Control channel S/P section    -   230: Multiplexing section    -   240: Pilot channel processing section    -   250: CCE aggregation processing section    -   260, 261: Control information count indicator generating section    -   300: Receiving section    -   301: Reception RF section    -   302: A/D section    -   303: Symbol timing detecting section    -   304: GI removing section    -   305: FFT section    -   310: Control channel decoding section    -   311: CCE selecting section    -   312: QPSK demodulation section    -   313: Viterbi decoder section    -   314: CRC inspection section    -   320: Demultiplexing section    -   330: Channel compensation section    -   340: Channel estimating section    -   350: P/S section    -   360: Channel compensation section    -   370: CCE reconfiguration section    -   380: Data demodulating section    -   390: Turbo decoding section    -   400, 401: Control information count indicator detecting section    -   410: Starting CCE selecting section

1.-19. (canceled)
 20. A mobile station device which receives a downlinkcontrol channel, the downlink control channel including one or morecontrol channel elements, the control channel element including aplurality of time/frequency resources, wherein, in connection with adomain including the plurality of control channel elements to which thedownlink control channel is decoded, the mobile station device controlsthe number of the control channel elements which are included in thedomain, the control being made in response to the number of the downlinkcontrol channel to which decoding and detecting are performed.
 21. Amobile station device which receives a downlink control channel at aplurality of frequency bands, the frequency band including a pluralityof continuous subcarriers, wherein the mobile station device receivesinformation indicating the number of the downlink control channel whichincludes control information of the mobile station device for eachfrequency band, and decodes the downlink control channel until theindicated number of the control information of the mobile station deviceare detected.
 22. The mobile station device according to claim 21,wherein the information indicating the number of the downlink controlchannel indicates the number of the downlink control channel includingeach control information of the mobile station device in a time domainframe to which the information indicating the number of the downlinkcontrol channel is arranged.
 23. The mobile station device according toclaim 21, wherein a control channel element includes a plurality oftime/frequency resources, and wherein the information indicating thenumber of the downlink control channel is arranged to the predeterminednumber of control channel element.
 24. A wireless communication systemcomprising a plurality of mobile station devices and a base stationdevice which transmits a transmission signal to a mobile station device,the transmission signal including a downlink control channel, thedownlink control channel including one or more control channel elements,the control channel element including a plurality of time/frequencyresources, wherein the base station device transmits a signal includingthe downlink control channel, the transmission is made using one or morecontrol channel element in a domain, the domain including a plurality ofcontrol channel elements to which the downlink control channel isdecoded, and wherein, in connection with a domain including a pluralityof control channel elements to which the downlink control channel isdecoded, the mobile station device controls the number of the controlchannel element which is included in the domain, the control being madein response to the number of the downlink control channel to whichdecoding and detecting are performed, and decodes the downlink controlchannel in the domain.
 25. A wireless communication system comprising aplurality of mobile station devices and a base station device whichtransmits a transmission signal to a mobile station device, thetransmission signal including a downlink control channel, the downlinkcontrol channel including one or more control channel elements, thecontrol channel element including a plurality of time/frequencyresources in a plurality of frequency bands, the frequency bandincluding a plurality of continuous subcarriers, wherein the basestation device transmits information and one or more downlink controlchannels, the information indicating the number of downlink controlchannel, the downlink control channel including control information ofthe mobile station device for each frequency band, and wherein themobile station device receives the information indicating the number ofthe downlink control channel which includes the control information ofthe mobile station device for each frequency band, and decodes thedownlink control channel until the indicated number of the controlinformation of the mobile station device are detected.
 26. A basestation device which transmits a downlink control channel to a mobilestation device in a plurality of frequency bands, the frequency bandincluding a plurality of continuous subcarriers, wherein the basestation device transmits information and one or more downlink controlchannels, the information indicating the number of the downlink controlchannel including control information of the mobile station device foreach frequency band.